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Discussion Starter · #1 · (Edited)
After scouring the web and this forum for information there just is not a lot of information about the differences between gen 1 rfb's and gen 2 rfb's. Having the gas head break on my Gen 1 after 5 years of use I had to get my gen 1 updated to a gen 2 at the factory.
My gen 1 rfb gas head broke after heavy use during a competition. The gun continued to function having a few short strokes in the process. Being completely satisfied with my gen 1, I just wanted the gen 1 fixed by replacing the gas head. Like most of the parts between gen 1 and gen 2 they are not interchangeable. So I ended up with a complete rifle swap to a gen 2.
Some notable differences are a smaller less machined round gas head with a smaller gas piston. The original gas head was more machined and the piston was rotated into it. These gen 1 gas heads were noted to break often when suppressed and over gased according to the factory. The new gas head vents downward and adjusts with the tip of a cartridge instead of the rear.
The piston is now linked to a spring attached to the carriers right recoil spring via an extension. I do not know what this is for other than to keep the piston in the gas head during firing.
The carrier now has two holes in the top both forward and aft.
The bolt is no longer chrome but some dull yellow brass like finish. There was an original problem the bolt flaking maybe this solved that?
Trigger is notably better... Not that the old one was bad.
That's about it. Very limited parts interchangeablity between gen 1 and gen 2.
Hope it shoots as well or better than it did. I'll find out tomorrow.
 

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I think most of the parts ARE interchangeable. I had a spring guide tube weld break years back. They said they may have to swap out all the 1st gen gas system, but I asked that they not unless absolutely necessary. Rifle came back still 1stgen gas with a gen 2 carrier fitted, but using gen1 spring and guide rods(my originals as I marked them to see what they would swap:) The only disappointment was the new carrier was thinner material than the gen1 was, part of the weight reduction design changes between gen 1 and 2 I guess...

The piston is not linked to the spring. They use an extended guide rod on the right side and put a spring on top of that rod that extends past the end of the rod to touch the rear of the gas piston. In the first gen, piston travel was stopped by those 3 teeth on the piston engaging companion teeth in the gashead bore. Lot of stress and hammering on those teeth plus a Lot of machining plus heat treating involved in the 1st gen piston and gashead. The extended guiderod is what stops the piston stroke in the second gens, with that spring providing some buffering. Simpler execution, a whole lot less machinework, and probably no heat treating(hard to QC) involved in the piston or gashead...

I have wondered a few times if that forward spring couldn't be adjusted/swapped to help tailor the gas required to cycle the action/tune the gas system...
 

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Discussion Starter · #3 ·
Seems like the only way a gen 1 can have an extended service life is to custom tune the gas system to one type of ammo ( something I never did) the gas head teeth are a high stress area. I liked the simplicity of the gas system in the gen 1 in an otherwise complicated rifle. Sad to see it go.
I feel like the rfb is going to be phased out because of those complexities and the rdb will be scaled up to 308 as a replacement. I see the two guns as redundant in that case.
I guess a lot of parts really are interchangeable but if there is something wrong with the gas port then almost the whole rifle has to be changed. Wish the manual reflected those changes.
Too bad the new changes with less machining did not drop the rfb price but when you are the only game in town you can do what you want.
Still curious about what my yellow bolt is made of and why it was switched from chrome?
 

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I forget what it is called, but it is a form of industrial hardchrome/ceramic. I recall someone putting a name to it in one of the threads on this forum, but it escapes me right now. Probably just as durable, but less issues with coating failure/flaking. It is also probably easier to apply:)

They say the RFB production will continue... As long as they are selling steadly, I would see no reason to not believe this as each successive rifle gets cheaper to produce as the tooling and assembly facilities are paid off... IE: no sense slaughtering the cash cow before she is done producing milk... I guess time will tell. What really surprises me is that someone has not seen KT's success with the RFB and marketed an alternative 30CAL bullpup...
 

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Still curious about what my yellow bolt is made of and why it was switched from chrome?
The yellow bolt has a titanium nitride finish for hardening and durability, similar to both the inside and outside of many current KT barrels, including the RFB (just not yellow). It does not flake like chrome plating, and advertised as 3X the hardness.

http://www.onesourcetactical.com/titanium-nitride-slide-finish-1.aspx#.VxGG1dP6zs0

Edit: I have both a Gen 2 hunter, and a Gen 1 carbine. I purchased a Gen 2 suppressor piston for the hunter. It worked great. I literally begged KT to sell me a Gen 2 gas cylinder and piston, to convert the Gen 1. They insisted I send the rifle in, and they would convert it. What I received back in the upgraded RFB was a new bolt carrier group, gas block, gas cylinder, barrel, standard piston, and suppressor piston, (it already had the upgraded bolt) -- all gratis.

It now works great suppressed, and is my favorite all around rifle. Kudos on Kel-Tec, and I'm definitely not looking a gift horse in the mouth.
 

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Discussion Starter · #7 ·
Thanks for the information. At first I was a little disappointed with the appearance of my gen 2 but now after hearing how much better the durability, function, and materials are, I'm excited to put it through its paces. I have a week long Appleseed boot camp this week and will have a report to follow. Thanks again.
 
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